Manufacturers of products who ship their goods in a container, such as a cardboard box or carton generally referred to as a case, often desire to apply a label to the outside of the case. The label typically has identifying information, such as product codes, stock or lot numbers, bar codes and shipping data, printed thereon to identify the manufacturer of the goods, the contents of the case or the destination of the case. The label has a first side on which the identifying information is printed, and a second side opposite the first side which is coated with a pressure sensitive adhesive. The adhesive side of the label is applied to the outside of the case so that the identifying information on the printed side of the label is available to be read either manually or by an electronic scanner.
If the identifying information for many successive cases is the same, it can be pre-printed on the label, for example, by a flexo-graphic printing process. Often, however, the identifying information varies for each case, or for a series of cases, so that the manufacturer, the contents, or the destination of each case, or series of cases, can be separately identified. The present practice is to print the variable identifying information on labels, commonly known as linerless label stock because the adhesive side of the label is not protected by a liner coated with a release agent, immediately before the label is applied to the case. The process of printing variable information on each label, or on a series of labels, is known as variable image printing.
Label stock, however, is expensive relative to conventional tape and requires specially designed equipment to apply the label to the case. Conventional tape is manufactured and wound on a spool which can be easily mounted onto a tape unwind spool spindle driven by a conventional motor. Label stock, on the other hand, is typically manufactured in thin sheets and is applied to the case by a tamp head positioned on the end of a pneumatic or hydraulic tamp. The label stock is held on the face of the tamp by creating a vacuum behind the tamp head and is transferred to the case by activating an air jet in the direction of the case. The equipment required to position the label stock on the tamp head and to transfer the label to the case is susceptible to misfeeding and malfunctioning. Thus, the cost of variable image printing on label stock and the complexity of applying the label to a case reduces the efficiency and productivity of the labeling process.
The same manufacturers often utilize automated production lines to package, seal, label and route cases containing the goods. A typical production line includes a sealing station, at which the case is sealed, for example with an adhesive sealing tape, and a labeling station, at which a label is applied to the case. If variable information is to be printed on the label, the labeling station also includes a variable image printer. It has long been recognized that combining the sealing and labeling stations would result in increased productivity, and thus reduce costs. However, the full advantages of a combined sealing and labeling station cannot be realized unless the combined station is capable of printing variable identifying information onto a label and applying the label to a case at the speed of the production line. The speed of a conventional production line is between about eight and about twenty-four inches per second, and is preferably about sixteen inches per second.
Manufacturers presently combine the tasks of sealing and labeling cases only when the information to be printed on the labels is constant. This is accomplished by utilizing adhesive sealing tape having the identifying information pre-printed on the face of the tape. It has previously proven to be difficult for manufacturers to combine the tasks of sealing and labeling when the information to be printed on the labels is variable. The primary reason is that the adhesive side of the tape is exposed as the tape unwinds from the tape spool and must be supported opposite the pressure of the print head as the ink is transferred to the face of the tape. As a result, the tape adheres to the support structure (typically one or more rollers) or the adhesive from the tape accumulates on the support structure as will be described. Another reason is that the tape must be printed and applied at a rate that is compatible with the speed of the production line.
The adhesive side of the tape can be supported by a print, or platen, roller having a synthetic nonstick resin, such as a TEFLON.RTM., silicon or plasma coating, or that is coated with a release film. However, the type of adhesive sealing tape typically selected for sealing cases generally utilizes an exceptionally strong adhesive to insure that the case does not break open during handling. Over time, the adhesive can accumulate on the roller, or remove the release film from the roller, thereby causing the tape to inadequately label or seal the case. Thus, the condition of the roller and the tape must be monitored closely, and the roller must be re-coated at regular intervals, thereby decreasing the productivity of the production line and increasing the maintenance required to operate the combined labeling and sealing station on the production line.
A coating that must be wetted to activate the adhesive could be used, and the tape could be variable imaged printed before the adhesive is wetted. The platen roller would then be able to support the dry adhesive side of the tape against the pressure of the print head while the variable identifying information is printed on the face of the tape. However, dry adhesive sealing tapes which require wetting prior to application do not typically produce an adhesive bond that is adequate to insure that the case does not break open during handling. Further, the use of a dry adhesive tape that must be wetted to activate the adhesive would require the introduction of an additional mechanism to wet the adhesive. Such an additional mechanism would increase the complexity of the sealing and labeling station, thereby decreasing the productivity of the production line and increasing the maintenance required to operate the combined station on the production line.
As is apparent, there is a need for an apparatus and process for variable image printing on tape instead of label stock. More specifically, there is a need for an apparatus for variable image printing on tape that is to be applied to a shipping case to convey identifying information, such as product codes, stock or lot numbers, bar codes and shipping data, which identifies the manufacturer of the goods, the contents of the case or the destination of the case.
In particular, a sealing and labeling station is needed that is capable of printing variable identifying information on adhesive sealing tape without decreasing the productivity of the station, or increasing the complexity and maintenance of the station. Such a sealing and labeling station, for example, would make it possible to combine the tasks of sealing and labeling a case on a production line with variable identifying information.
Accordingly, it is a principle object of the invention to provide an apparatus and process for variable image printing on tape instead of label stock. More particularly, it is an object of the invention to provide a thermal printer for printing variable identifying information, such as product codes, stock or lot numbers, bar codes and shipping data, on tape that is to be applied to an exterior surface of a shipping case to identify the manufacturer of the goods, the contents of the case or the destination of the case.
It is a further object of the invention to provide a combined sealing and labeling station including a thermal printer for sealing and labeling a case on a production line with adhesive sealing tape having variable identifying information printed on the tape.
It is yet another object of the invention to provide a combined sealing and labeling station including a thermal printer for sealing and labeling a case on a production line that is capable of printing variable identifying information on the face of adhesive sealing tape without decreasing the productivity or increasing the complexity and maintenance of the combined station.